With the advent of broadcasting in accordance with Advanced Television Systems Committee (ATSC) digital television (DTV) standards, particularly high definition television (HDTV), the need for displaying film material on high definition television receivers arises. The field rate—the number of full-field images or frames per second, expressed in Hertz (Hz)—for high definition television is generally at least 50-60 Hz and up to 100-120 Hz. However, for historical electro-mechanical reasons, motion picture cameras employed in creating film material have conventionally operated at a capture rate of 24 frames per second. While modern motion picture cameras have been improved, much film exists which was recorded at that previous standard capture rate. Moreover, film captured at 24 Hz provides, when transferred to high definition resolution, comparable quality to high definition cameras, eliminating any incentive for film production companies to discontinue use of traditional cameras in favor of purchasing high definition cameras.
Conversion of film material to higher display field rates is generally performed by simple field repetition, utilizing known 3:2 pull-down or 2:2 pull-down techniques. However, such field rate up-conversion by simple field repetition results in each movement or motion phase (i.e., frame) being displayed multiple times, with moving objects appearing slightly displaced from their expected space-time position in the repeated motion phases. This results in motion blurring for slow object movement and motion jerkiness for fast object movement.
To improve the motion portrayal of up-converted film material, the number of motion phases must be increased. Motion-compensated up-conversion techniques have been developed for this general purpose in up-converting film material to standard definition (SD) television. See, for example, G. de Haan et al, “IC for Motion Compensated De-interlacing, Noise Reduction, and Picture Rate Conversion,” International Conference on Consumer Electronics (ICEE) 1999, pp. 212-213 and O. A. Ojo and G. de Haan, “Robust Motion-Compensated Video Up-Conversion,” IEEE Tr. On Consumer Electronics, vol. 43 no. 4 pp. 1045-1056 (November 1997).
In addition to higher frame rates, high definition television also employs image sizes which are four to six times greater than either film or standard definition television material. Therefore, for high definition television, the memory size and memory bandwidth requirements of motion estimation are four to six times greater than corresponding requirements for standard definition material due to the higher pixel resolution. These requirements pose a feasibility problem for consumer solutions.
There is, therefore, a need in the art for an improved film-to-video motion compensation technique for up-converting film material to high definition television.